Process of brewing tea leaves contained in a capsule

ABSTRACT

The invention concerns a process for the preparation of a beverage in a beverage machine with a capsule comprising an enclosure containing tea leaves comprising the steps of: a) introducing water in the capsule to submerge the tea leaves in the capsule enclosure, then b) introducing water at a soaking flow of at most 80 ml/min, then c) introducing water in the capsule until the required volume of beverage is delivered, wherein during at least one period of step b), water is introduced in the capsule at least once at a stirring flow superior the soaking flow to stir tea leaves.

The present invention relates to a process for brewing tea leaves orother kinds of herbal leaves contained in a beverage producing capsule.

Different beverage capsules for brewing beverages in a suitable beveragemachine are known. One commercially successful capsule system forextracting beverage from capsules consists in placing an air- andwater-impermeable capsule into an extraction device, injecting hot waterinto the capsule and releasing the liquid extract out of the capsule.Most of the beverages produced by these capsules are coffee or beveragesissued from the dissolution of soluble liquid or powder ingredients.

Concerning the production of tea beverage, WO 2007/042414 describescapsules more particularly suited for tea beverages produced from acapsule containing leaf tea product and the like. Quality of a teabeverage is highly dependent on the quality of the leaf tea ingredients,i.e., the tea origin used (soil, drying, blending, etc.) and theirstorage conditions. For instance, tea ingredients are usually sensitiveto oxygen and light. Preferred tea ingredients are taken from looseleaves, chiselled or broken in small fragments. However, brewingconditions are also important to take full advantage of the quality ofthe ingredients used.

Usually beverage machines process all the capsules the same way becausethey process always the same product, coffee for example. Other machineshave also been developed for producing different kinds of beverages:they are able to produce either coffee or chocolate or tea orcappuccino. For example EP 1 440 640 describes such a type of machine.This machine enables the production of different beverages (coffee,chocolate, milk, . . . ). It mentions that the operational parameters ofthe machine are adjusted according to the nature of the ingredients, yetno information are given concerning these parameters

Concerning the particular preparation of beverage from capsulescomprising tea leaves, it has been noticed that the usual brewing stepsused for coffee and other beverages could not lead to optimalpreparation of a tea beverage. In particular it is known that the timefor extracting tea leaves is quite longer than for extracting coffeefrom roast and ground coffee because tea leaves must hydrate and openthemselves before extraction occurs. Then the process of extraction ofroast and ground coffee does not lead to optimal brewing of tea leaves.

Besides, there exists a large variety of different tea leaves : black,green, white, red, herbal teas perfumed with a lot of different aromas.Each of these leaves can require specific extraction. On the contrary,roast and ground coffees of different origins are all extractedaccording to the same process.

Lastly the long time for extraction of tea leaves can be perceived as adisadvantage when a tea beverage is prepared by a machine compared tothe classical preparation in a tea pot. Yet shorter preparation of teabeverage leads to lower quality of extraction. Then is there a need tooptimize the tea extraction length time while maintaining the quality ofthe extraction.

The present invention aims at solving the problem of quality byimproving the brewing process of tea leaves in a process of preparationof tea beverage from a capsule containing tea leaves. The presentinvention aims also at solving the problem of brewing tea leaves in aprocess of preparation of tea beverage from a capsule containing tealeaves in the shortest time as possible while maintaining an optimalextraction of the tea extract from the tea leaves.

The present invention aims also at solving the problem of brewing tealeaves of very different types enclosed in a capsule with the samebeverage machine by proposing a process adaptable to each type of tealeaves.

According to a first aspect, the invention concerns a process for thepreparation of a tea beverage in a beverage machine with a capsulecomprising an enclosure containing tea leaves comprising the steps of:

a) introducing water in the capsule to submerge the tea leaves in thecapsule enclosure, thenb) introducing water at a soaking flow of at most 80 ml/min, thenc) introducing water in the capsule until the required volume ofbeverage is delivered,wherein during at least one period of step b), water is introduced inthe capsule at a stirring flow superior to the soaking flow to stir tealeaves.

The process of the present invention is adapted for the preparation of atea beverage by introduction of hot water in a capsule containing tealeaves, the capsule presenting an inlet for introducing water and anoutlet for evacuating the extracted tea beverage. The inlet and/or theoutlet can be preformed or produced by puncturing means of the machine.

According to the invention, in the first step a), water is introduced inthe capsule to at least submerge all the tea leaves in the capsuleenclosure. According to a preferred embodiment of the invention, duringstep a), a volume equivalent to the volume tea leaves enclosure of thecapsule is introduced so as to be sure that the leaves are submerged bywater. During this step a), the tea leaves are wetted. Preferably,during step a), water is introduced at a flow of at least 150 ml/min.Such a flow value enables the rapid filling of the capsule to manageoptimal beverage preparation time length. The value of this flow canalso depend from the type of heater used to heat the water and itsability to provide hot water at high flow rates.

Immediately after step a) and the wetting of the leaves, step b) startsduring which water is introduced at a soaking flow of at most 80 ml/min,preferably at most 50 ml/min, generally comprised between 20 and 80ml/min. Such a soaking flow aims at leaving tea leaves quiet so thatthey can unfold. According to a specific mode, the soaking flow can benull. If this soaking flow is not null, the introduction can eithercomplete the filling of the tea leaves enclosure or leads to theoverflow of this enclosure; in this last case, it produces a drip flowin the container or cup placed at the outlet of the capsule. During thisstep b), the extraction of tea begins. Generally the time length of stepb) is at least 5 seconds, preferably at most 50 seconds. According tothe invention, during step b) water is briefly introduced during atleast one period (b′) in the capsule at a stirring flow superior to thesoaking flow to stir tea leaves. During this soaking step b) thatcorresponds to a quiet period during which tea leaves are at rest onaccount of no introduction of water or introduction of water at lowflow, the short introduction of water at a stirring flow superior to thesoaking flow creates a turbulent jet of water able to move and stir thetea leaves and to redistribute the leaves in the capsule before they areagain left at rest. Due to this stirring and redistribution of the tealeaves, extraction of tea leaves is boosted because immobilization oftea leaves after step a) creates places where tea extract concentrationis high and then inhibition of further extraction in the area near fromthese places. In order to provide a jet of water sufficient to stir tealeaves, the stirring flow is preferably at least greater than 150ml/min. Several stirring jets of water can occur separated by restperiods during which the water flow rate stays inferior or equal to 80ml/min or null. In step b), the number of periods during which water isintroduced in the capsule to stir tea leaves, the time length ofthis/these period(s) and the total time length of step b) can beadjusted in function of at least:

the nature of brewed tea leaves, in particular their size, theirdryness, their flavour, andthe desired strength of the final beverage.

Preferably in step b) of the process of the present invention, water isintroduced in the capsule to stir tea leaves one or two times(corresponding to two stirring periods (b′)). Generally, the time lengthof each period during which water is introduced in the capsule to stirtea leaves is inferior to 5 seconds. The time length between two periodsduring which tea leaves are stirred preferably lasts during 5 and 15seconds.

Lastly during step c), the rest of the water necessary to provide thedesired volume of beverage is introduced in the capsule. Preferablyduring step c) water is introduced at a flow of at least 150 ml/min inorder to match the shortest beverage delivery time.

The different flow rates of water according to the different steps ofthe process can be set so that the total time for implementing steps a)to c) is comprised between 40 seconds and 2 min.

Generally water is introduced in the capsule with a temperaturecomprised between 30 and 95° C.

According to the preferred embodiment of the present invention, theprocess is implemented with a capsule comprising:

an enclosure containing tea leaves,a filtering wall delimiting at least one filtering side of theenclosure,an overflow wall that is positioned in the path of the brewed liquidafter the filtering wall and which comprises at least one overflowaperture or is associated with at least one puncture means or,respectively, puncture indication means capable of producing or,respectively, indicating at least one overflow aperture. Preferably thefiltering wall extends from below a median horizontal plane passingthrough the enclosure when the capsule is oriented so that at least oneoverflow aperture or puncture means or, respectively the punctureindicating means, is placed above said plane. Such a capsule is morespecifically described in WO 2007/042414.

According to a second aspect, the invention concerns a beverageproduction system comprising:

beverage ingredient containing capsules comprising an identificationmember, anda beverage production machine for receiving said capsules, said machinecomprising reading means for reading the capsule identification memberin order to read information thereof and control means connected to thereading means and designed to control the operation of the beverageproduction machine in response to the read information,characterized in that the identification member provides instructions tothe machine for brewing tea leaves according to the process such asdescribed above.

This identification member can be of any nature like bar code, colourcode (identified by a visual sensor), RFID tag (identified by a RFsensor), indents, cut outs, protrusions, holes (identified by amechanical sensor), magnetic code, electronic code, induction code,conduction code . . . Preferably, the identification member is designedfor being physically contacted from outside and is covered by adeformable, displaceable, removeable and/or puncturable cover. Capsulespresenting this kind of identification member are described in EP 1 950150. Generally, the machine-readable information are selected in thelist of: the temperature of the water, the values of the water flows ofsteps a), b) and/or c), the number of stirring periods in step b), thetime length of the steps a), b) and/or c) and combinations thereof. Thebeverage machine in which is used said capsule comprises control meansdesigned to control: the values of the water flows of steps a), b) andc), the number of stirring periods in step b), the time length of thedifferent steps in response to the read information. Based on theinformation provided by the identification member, the control unit canthen vary the brewing parameters especially the water flow of steps a),b) and c), the number of stirring periods in step b), the time length ofthe different steps flow rate for the brewing of different tea beveragesaccording to capsules containing leaf tea ingredients having differentcharacteristics and/or origins.

In the present application, the terms “capsule” means also “cartridge”or “package”. The term “capsule” will be preferentially used. The words“brewing” or “infusion” are used as synonymous. The term “brewing fluid”generally refers to the liquid that serves to infuse the beverageingredients, more generally, hot water.

In the present application, the term “tea” encompasses all type of leaftea such as green tea, black tea, white tea, chai tea, flavoured tea andherbal or fruit tea. The term “leaf tea/tea leaves” or “leaf ingredient”refers to brewable tea or other ingredients in whatever form such ascomplete, cut or chiselled leaves, small fragments of leaves, powder ordust.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics and advantages of the invention will be betterunderstood in relation to the figures which follow:

FIG. 1 is a diagram presenting the hot water flow introduced in thecapsule according to each step of the brewing process according to afirst embodiment of the invention;

FIG. 2 is a diagram presenting the hot water flow introduced in thecapsule according to each step of the brewing process according to asecond embodiment of the invention;

FIG. 3 is a schematic illustration of a capsule brewing system beforebrewing;

FIG. 4 is a schematic illustration of a the capsule brewing system ofFIG. 3 during brewing of the capsule.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the values of the hot water flows introduced in acapsule for each step of the process and the time length of introductionof these different flows according to a first embodiment of theinvention.

As illustrated in FIG. 1, in step a), the capsule is filled with hotwater with a flow of water of 150 ml/min. The volume of water that isintroduced in the capsule corresponds to the capsule teal leavesenclosure volume.

In step b):

the capsule is first filled with hot water again but at a lowest flow of50 ml/min so as to not stir the tea leaves and let the leaves unfold,then capsule is filled with hot water at a greater flow of 150 ml/min(step b′) during a short time of 3 seconds to stir the leaves in orderto redistribute them,then capsule is finally filled with hot water again but at the lowestflow of 50 ml/min so as to not stir the tea leaves an let theredistributed leaves unfold.

During step b), when the volume of injected water overlaps the capsuletea leaves enclosure volume, water gently drips through the capsuleoutlet inside a final cup or container.

In step c), the capsule is filled with hot water firstly at a flow of150 ml/min and then rapidly at a flow of 225 ml/min until the totaldesired volume of tea beverage flows through the capsule outlet andfills the cup.

The process of preparation and dispensing of the tea beverage ready tobe drunk lasts 51 seconds.

FIG. 2 illustrates the values of the hot water flows introduced in thecapsule for each step of the process and the time length of introductionof these different flows according to a second embodiment of theinvention.

In step a), the capsule is filled with hot water with a flow of water of150 ml/min. The volume of water that is introduced in the capsulecorresponds to the capsule volume.

In step b):

no hot water is introduced in the capsule so that the tea leaves canstay at rest and unfold. Yet, the pump is not stopped during this shortperiod to avoid the stagnation of water in the pump and the developmentof scale; hot water flow is just derived from capsule inlet and sent towaste.then capsule is filled with hot water at a flow of 150 ml/min (step b′)during 3 seconds to stir the leaves and redistribute them,then the flow of hot water is derivated to waste so that no flow entersthe capsule and that the redistributed leaves can stay at rest andunfold.

In step c), the capsule is filled with hot water firstly at a flow of150 ml/min and then rapidly at a flow of 225 ml/min until the totaldesired volume of tea beverage flows through the capsule and fills thecup.

The process of preparation and dispensing of the tea beverage ready tobe drunk lasts only 51 sec.

FIGS. 3 and 4 illustrate a capsule system of which construction isparticularly adapted for the implementation of the process of thepresent invention.

A capsule system 1 is provided that comprises a capsule 2 and a beveragebrewing device 10. For simplicity, the beverage brewing device is onlyschematically depicted and may, in reality, comprise additionaltechnical features within the normal knowledge of the person skilled inthe art. The capsule comprises an enclosure 20 containing beverageingredients such as leaf tea and the like. The enclosure is demarcatedby a cup-shaped housing 21 and a filtering wall 22 that is fixedlyattached to peripheral inner step 23 of the housing 21. The enclosure ispreferably impermeable to gas and light. The housing may encompassdifferent cross sections such as a circular, ellipsoid, square,rectangular or polygonal section that determine as a matter of fact thegeneral profile of the filtering wall 22. The enclosure is sized toaccommodate a dose of leaf beverage ingredient of typically aboutbetween 1 to 10 grams, preferably 2 to 5 grams. The dose of leafingredient may depend on the final volume of beverage to produce. For anindividual cup of tea, a typical dose can be of about 2 grams whereasfor a tea pot, a typical dose can be of about 8 to 10 grams. As clearlyapparent in FIG. 3, the capsule is positioned relative to the brewingdevice so that the filtering wall 22 extends substantially vertical andfrom substantially the bottom of the enclosure. For this, the capsule ispreferably positioned in a “vertical” arrangement in the brewing device1. The cup-shaped housing 21 can be so oriented with its large openingand its bottom oriented in a vertical position.

Importantly, the capsule comprises an overflow wall 3 with an overflowaperture 25 placed at least above the median horizontal plane P of theenclosure. The filtering wall 22 and the overflow wall 3 are spacedapart a short distance sufficient to create an interstitial space “s”that is supposed, without being bound by theory, to work as a sort of“siphon” that can promote the upward motion of the denser beverageportion that is predominantly localized in the bottom of the enclosure.

Both the sealing wall and the housing can be made of oxygen barriermaterials and the enclosure can be substantially free of oxygen so thatthe freshness of the beverage ingredients can be preserved during anextended period of time. The sealing wall can be a flexible membrane ora semi-rigid plastic part. A puncturable sealing membrane is preferredsuch as a monolayer or a multi-layer membrane, typically, laminates ofPET/Aluminium/PP, PE/EVOH/PP, PET/Metallised/PP, aluminum/PP. Theenclosure is preferably oxygen free and may contain flushed inert gassuch as N₂, N₂O or CO₂.

The capsule can further comprise a cover 4 that is also attached to therim 24 of the housing 21 and overlaps the sealing wall 3. The coverforms an internal channel 40. An identification member 51 can be presenton the cover (or even under the cover). This identification membercontains information about the brewing parameters to be implemented toget the better brewing for the tea leaves present inside the capsule.

The shape of the housing of the capsule is not very critical. Preferenceis given to a trunconical, ellipsoidal or hemispherical shapes fordifferent reasons. This allows a larger surface for the exit of thebeverage through the sealing wall when perforated and a reduction of theinside pressure. The housing can also be manufactured industrially atlower cost by plastic thermoforming or aluminium deep drawing. Thisshape with smoother corners also favours the removal of the handlingmembers and so ejection of the capsule.

Turning to the brewing device 10, it comprises capsule handling members30, 31 that are configured to hold the capsule in the “vertical”arrangement as defined. These handling members 30, 31 can be machinejaws or any suitable mechanical enclosing means that can open and closeabout the capsule and can maintain it firmly in place. There is no needfor providing high closing forces since the involved fluid pressure inthe capsule remains relatively low and, preferably, as close as possibleto the atmospheric pressure. Also, since the capsule can withstand thelow brewing pressure therefore the capsule does not necessarily need tobe entirely enclosed but simply held water tightly in place duringbrewing. This participates to a simplification of the machine and itreduces machine costs.

The brewing device comprises a water supply 32, such as a water tank, awater pump 33, a heater 34 and a hot water injection line 35 that ismanaged through the handling member 30. The brewing device may alsocomprise a controller 39 and a user interface board (not shown) tomanage the beverage preparation cycles as known in the art. Abackpressure valve 36 can be provided to lower the pressure at the entryside of injection member 38 such as a needle(s) or blade(s) creating awater inlet in the capsule. Of course, the backpressure valve could beomitted and a low pressure pump could be used that delivers fluid at lowpressure. Medium to high pressure pump may however be preferred becauseof their robustness and reliability and so used in combination with abackpressure valve.

The brewing device may further comprise a means 37 for perforating thecover 4 and creating a beverage outlet. As shown in FIG. 3, theperforating means 37 can be activated after closing of the handlingmembers 30, 31 about the capsule. The perforating means is forced orguided through the cover 4. The perforator can be driven by a solenoidor any other equivalent drive means or even manually.

The brewing device may further comprise a detection unit 50 to convertthe information of the identification member 51 of the capsule intobrewing instructions through the controller 39. In the present theinvention, the information especially varies according to the tea leavespresent inside the capsule. The information provide to the control unit39 instructions so that the steps a), b) and c) of the process of thepresent invention is implemented with specific features adapted for eachtype of tea leaves that are: the values of water flow of steps a), b)and c), the number of stirring periods in step b), the time length ofthe different steps.

Preferably the information can be read from the capsule 1 in anon-optical manner, as the optical reading e.g. using a bar code has thedisadvantages of having a negative impact on the aesthetic impression ofthe outer appearance of the capsule and of being prone to failure due tothe legibility of the bar code in the environment of the beverageproduction process. Preferably the information is coded in a digitalmanner. The information can be coded by a modulation of the surfacestructure of a face of the capsule 1. E.g. a hole or a recession canrepresent one logical sate (e.g. “0”), while another surface state (“norecession” or “no hole”) can represent the other logical state (e.g.“1”). Replacing the bar code by a surface modulation which can then bedetected in a non-optical manner (or even in an optical manner) enhancesthe reliability of the information reading from the capsule.

In relation to FIG. 4, the method of the invention works as follows. Acapsule is inserted in the brewing device and the capsule handlingmembers 30, 31 are closed about the capsule to position it with thesealing wall being substantially vertically oriented. An outlet apertureis created by the perforating means 37 that punctures the cover 4 and iswithdrawn to leave the aperture opened. On the opposite side of thecapsule, the fluid injection member 38 is introduced in the capsule'senclosure. Hot water is thus injected in the capsule at relatively lowpressure, preferably, at a pressure not exceeding 0,2 bar. Hot waterslowly fills the capsule in and submerges the beverage ingredients inthe enclosure. The brewed beverage is filtered through the filteringwall 22. A denser portion 5 of the beverage may tend to settle in thebottom of the enclosure; which portion is also filtered through thefiltering wall since it is properly placed adjacent this portion. Thedenser beverage is evacuated through the interstitial space “s” ascaused by the variation of pressure between the lower part of the spaceand the upper part of said space therefore acting similarly to a“siphon”. The rest of the beverage is also filtered also by passingthrough the filtering wall at different vertical levels up to the upperlevel of the fluid in the enclosure and is evacuated to the overflowaperture 25.

It should be noted that the overflow aperture should preferably beplaced above the ¾ of the total height of the enclosure and evenpreferably be placed above the ⅘ of the total height of the enclosure;thus ensuring a more complete submergence of the beverage ingredientsand a slower evacuation of the beverage from the enclosure which favoursa better infusion process.

The “total height” of the enclosure is meant to be the total distanceseparating the lowermost point of the enclosure to the uppermost pointof the enclosure when the capsule is positioned in the beverage machineready for the brewing operation. In a possible mode, the filtering wallcan be substantially equal to the total height of the enclosure.

The principle of the brewing method according to FIGS. 3 and 4encompasses different variants and equivalences.

For instance, the overflow wall 3 may not be perforated but may bepre-opened by a pre-cut overflow aperture. The pre-cut overflow aperturemeans an aperture which has already been made at the manufacturing stageof the capsule. Freshness of the beverage ingredients may so bepreserved by different means such as by an airtight closed cover with asealed outlet that is unsealed just before brewing or by the use of anairtight overwrap package that encloses the capsule.

The capsule may also be conceived without the cover 4 and itschannelling function. In which case, the front handling member 31 may bedesigned to collect the brewed liquid as it passes the overflow wall 3and travels down to the recipient.

1. Process for the preparation of a beverage in a beverage machine usinga capsule comprising an enclosure containing tea leaves comprising thesteps of: a) introducing water into the capsule to submerge the tealeaves in the capsule enclosure; b) introducing water at a soaking flowof at most 80 ml/min; c) introducing water in the capsule until arequired volume of beverage is delivered; and during at least one periodof step b), water is introduced into the capsule at a stirring flowgreater than the soaking flow to stir tea leaves.
 2. Process accordingto claim 1 wherein during step a), water is introduced at a flow of atleast 150 ml/min.
 3. Process according to claim 1, wherein during stepb), the soaking flow is null.
 4. Process according to claim 1, whereinthe length of time of the at least one period during which water isintroduced into the capsule at a stirring flow greater than the soakingflow to stir tea leaves is less than 5 seconds.
 5. Process according toclaim 1, wherein the length of time of step b) is at least 5 seconds. 6.Process according to claim 1, wherein during step b) the stirring flowis at least greater than 150 ml/min.
 7. Process according to claim 1,wherein during step c), water is introduced at a flow of at least 150ml/min.
 8. Process according to claim 1, wherein water is introduced ata temperature of between 30 and 95° C.
 9. Process according to claim 1using a capsule comprising: an enclosure containing tea leaves, afiltering wall defining at least one filtering side of the enclosure,and an overflow wall that is located in a path of the brewed liquidafter the filtering wall and which comprises at least one overflowaperture.
 10. Process according to claim 1, wherein the filtering wallextends from below a median horizontal plane passing through theenclosure when the capsule is positioned so that the overflow apertureis located above the plane.
 11. A beverage production system comprising:beverage ingredient containing capsules comprising an identificationmember; and a beverage production machine for receiving the capsules,the machine comprising reading means for reading the capsuleidentification member in order to read information thereof and controlmeans connected to the reading means and designed to control theoperation of the beverage production machine in response to the readinformation, the identification member provides instructions to themachine for brewing tea leaves according to the process of introducingwater into a capsule to submerge tea leaves in the capsule enclosure,introducing water at a soaking flow of at most 80 ml/min, introducingwater in the capsule until a required volume of beverage is delivered,and during at least one period, water is introduced into the capsule ata stirring flow greater than the soaking flow to sir tea leaves.
 12. Abeverage production system according to claim 11, wherein themachine-readable information is selected from the group consisting of:the temperature of the water, the values of the water flows, the numberof stirring periods, the time length of the steps; and combinationsthereof.
 13. A beverage production system according to claim 11, whereinthe capsules comprise: an enclosure containing tea leaves, a filteringwall defining at least one filtering side of the enclosure, and anoverflow wall that is located in a path of the brewed liquid after thefiltering wall and which comprises at least one overflow aperture.
 14. Abeverage production system according to claim 13, wherein the filteringwall extends from below a median horizontal plane passing through theenclosure when the capsule is positioned so that the overflow apertureis located above the plane.